Input/output device for connection and disconnection of active lines

ABSTRACT

There is provided an input/output device having of not exerting any adverse influence on other expansion devices connected to a system bus at the time of insertion or removal. 
     An expansion device  800  comprises an electronic circuit  400  and a MOS switch  300 , and is connected to a system bus (BUS) via a connector having long and short pins. The expansion device  800  two power supply systems, namely a stable power supply  250  and an unstable power supply  260 . At the time of insertion or removal of the expansion device  800 , power is provided to the MOS switch  300  and a high impedance maintaining circuit from the stable power supply via a pair of long pins, so as to reliably place the MOS switch  300  in a high impedance state, inside the expansion device the high impedance maintaining circuit  350  drives an open/close control terminal, and power is provided to the electronic circuit  400  from the unstable power supply  260.    
     At the time of insertion or removal, adverse influence is not exerted on the signal transmission on the system bus, and effects of load variation on the main power supply are reduced.

This is a continuation of application Ser. No. 09/932,973, filed Aug.21, 2001 (now U.S. Pat. No. 6,393,509); which is a continuation of Ser.No. 09/499,897, filed Feb. 8, 2000 (now U.S. Pat. No. 6,289,407); whichis a continuation of Ser. No. 09/043,517, filed Mar. 23, 1998 (now U.S.Pat. No. 6,038,615), the entire disclosures of which are herebyincorporated by reference.

TECHNICAL FIELD

The present invention relates to an input/output device for connectionand disconnection of active lines, and particularly to a device forconnecting and disconnecting other electronic circuit devices to andfrom a network of signal circuits operating independently of anoperating system bus, without causing the operation of the system bus tostop.

BACKGROUND ART

In recent computer systems, as well as high speed and high performanceprocessing devices, there has also been a demand for improvements in thetransfer rate of a system bus which is the transmission path for theresults of processing. Also, accompanying the diversification ofsystems, there has been an increasing necessity to connect electroniccircuits having various functions mainly to the system bus. The rolesplayed by computer systems have become much more serious, and in orderto maintain expansion devices including the aforementioned electroniccircuits, there is a tendency to not permit system stoppages, and a needhas arisen to connect or disconnect these expansion devices using activelines. On the other hand, in shared bus system type configurations,there is also a need for a way of settling the bus signal waveformquickly, for each expansion device, in order to achieve high speedoperation.

Conventionally, as disclosed in Japanese Patent Laid-open PublicationNo. Hei 5-12777 (which will be referred to as publication 1), there hasbeen known a device in which power is supplied beforehand using a cord,etc., and disable control (open control) of bus drivers is carried out.As disclosed in Patent laid-open publication No. Hei 4-171520(publication 2) a power supply and an open/close control line of adriver are connected to bus circuits by a long pin, while other bussignal lines are connected to the bus circuits by a short pin. At thetime of insertion of a device, corruption of signals on the bus causedby the insertion is prevented by disabling the open/close signal line ofthe drivers in advance. However, in publication 1, the procedure ofconnecting the cord beforehand at the time of insertion or removal iscomplicated, while in publication 2 an open/close control line must bedisabled beforehand. In either case, since it can not be guaranteed thatthe drivers will be disabled when insertion or removal is carried outcarelessly, there is a possibility of problems arising such as thesystem crashing, for instance.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide an input/output devicecapable of connecting and disconnecting active lines, and particularlyan input/output device in which the insertion or removal of expansiondevices does not inhibit bus signal transfer of other electronic deviceson a high speed bus due to a disabled state being maintained at the timeof insertion or removal using transfer gates with small signal delay inthe input output device.

Another object of the present invention is to provide an input/outputdevice capable of connecting and disconnecting active lines, andparticularly an input/output device in which the internal power supplysystems of expansion devices are multiplexed, the influence on powersupplies is reduced at the time of inserting or removing expansiondevices, at the same time as ensuring that the maintaining of highimpedance of internal parts of the expansion devices, particularly theinput/output devices, does not become unreliable, and in which theoperation of electronic circuits not involved with insertion or removaldoes not become unreliable.

Still another object of the present invention is to provide a method,related to an input/output device, that can be applied to a high speedbus to rapidly settle the bus operating waveform by arranging insertionof transfer gates at locations a fixed short distance from a bus at theinput/output section of electronic circuits.

An input/output device of the present invention is connected to aplurality of electronic circuits and to a plurality of signal circuitnetworks having signal branch wires, these electronic circuit networksbeing arranged on printed circuit boards interconnecting the signalcircuit networks and on separate expansion devices, the expansiondevices having an input/output device power supply section for supplyingpower to the input output devices and being connected to the signalcircuit networks through connectors including a pair of long pins thatmake initial contact at the time of insertion and are the last thingseparated at the time of removal, and a pair of short pins that makecontact after the long pins at the time of insertion, and are separatedbefore the long pins at the time of removal, the input/output devicepower supply section being connected to a main power supply through thepair of long pins, the input/output device including a plurality oftransfer gates, the transfer gates having two input/output terminals andan open/close control terminal, one of the input terminals of theplurality of transfer gates being connected to the plurality of signalbranch wires through the pair of short pins while the other inputterminal of the plurality of transfer gates is connected to theelectronic circuits, and the open/close control terminal is connected toa positive or negative power supply of the input/output device powersupply section inside the expansion devices, through a resistor.

Further, an input device of the present invention is characterized inthat the open/close control terminals of the plurality of transfer gatesare connected to a control device for carrying out open/close control ofthe transfer gates, through the pair of long pins.

The control device of the present invention drives the open/closeterminal in synchronism with a reference signal used by the electroniccircuits to extract signal of the signal circuit networks.

Further, the control device of the present invention has connectionconfirmation means for confirming whether or not the plurality ofexpansion devices are connected to the signal circuit networks, and atleast one connection state register for establishing connection statesof the plurality of expansion devices that have been identified by theconnection confirmation means.

The control device of the present invention is further characterized inthat it has an open/close control register, and open and close for eachinput/output device is controlled by writing open or closed informationto a region of the open/close control register corresponding to eachinput/output device.

An expansion device of the present invention has an input/output devicepower supply section for supplying power only to the input/outputdevice, and a circuit power supply section for supplying power tocircuits other than the input/output device, the input/output powersupply section being connected to a main power supply through a firstpair of long pins, the circuit power supply section being connected tothe main power supply or to a different reserve charge power supplythrough a second pair of long pins.

The expansion device of the present invention is further characterizedin that it has an input/output device power supply section for supplyingpower only to the input/output device, and a circuit power supplysection for supplying power to circuits other than the input/outputdevice, the input/output power supply section being connected to a mainpower supply through a first pair of long pins, the circuit power supplysection being connected to the main power supply through a second pairof long pins.

The expansion device of the present invention is further characterizedin that it has an input/output device power supply section for supplyingpower only to the input/output device, and a circuit power supplysection for supplying power to circuits other than the input/outputdevice, the input/output power supply section being connected to a mainpower supply through a first pair of long pins, the circuit power supplysection being connected to a capacitor through a second pair of longpins, the capacitor being charged by the main power supply.

Still further, the input/output device of the present invention ischaracterized in that the capacitor is charged from the main powersupply through a resistor, or through a resistor and a diode.

Further, in the input/output device of the present invention, a circuitpower supply section is connected to the main supply through a pair ofshort pins.

An expansion device of the present invention is characterized in thatthe input/output device power supply section and the circuit powersupply section are wired onto a printed substrate for connecting theelectronic circuits, between spaces where there is no wiring material.

The expansion device of the present invention is further characterizedin that a pin on a connector for supplying power to the input/outputdevice power supply section and the circuit power supply section arearranged with maximum separation on the connector.

The input/output device of the present invention is connected to aplurality of electronic circuits and to a plurality of signal circuitnetworks having signal branch wires, and includes a plurality oftransfer gates. The transfer gates have two input/output terminals andan open/close control terminal. First signal branch wires connect oneinput/output terminal of the transfer gates and the signal circuitnetworks, while second signal branch wires connect the otherinput/output terminals of said plurality of transfer gates to theelectronic circuits. The open/close control terminal of the transfergates maintains a potential across the two input/output terminals toalways maintain a conductive state. Reflected waves of the signalcircuit networks are reduced by making the length of the first signalbranch wires less than 1.5 inches, and distribution loss of theelectronic circuits is reduced by making the length of the second signalbranch wires less than 1.5 inches.

Since the present has the above construction, a disable signal issupplied to the open/close control terminal of the transfer gates at thesame time as a stable power supply is provided to the transfer gates,even when expansion devices are inserted or removed, the input/outputterminals of the transfer gates are maintained at high impedance, and itis possible to minimize the effects on the system bus at the time ofinsertion or removal.

Further, in the present invention, a reserve charge power supply otherthan the main power supply for supplying power to a plurality ofexpansion devices is prepared, and the power supply systems inside theexpansion devices are arranged into stable power supply systemsconnected to a stable main power supply from initial insertion of theexpansion devices and unstable power supply systems connected to thereserve charge power supply at the time of insertion of the expansiondevices. From initial insertion of the expansion devices, by supplyingpower to transfer gates that require the input/output terminals to bereliably high impedance from the stable power supply systems andsupplying power to charge a capacitive load existing in the expansiondevices from the unstable power supply systems, it is possible to reducethe effects on the main power supply and to continue stable operation ofother expansion devices currently operating on the system bus, even atthe time of insertion or removal of the expansion devices. As long asthe main power supply can supply power smoothly it can also serve as thereserve charge power supply.

Also, by inserting transfer gates at positions fixed short distancesfrom a bus at the input output section of the electronic circuits, theeffects of reflections of the transfer gates at the electronic circuitside can be absorbed by the transfer gates, bus signal multiplexedreflected waves can be attenuated in a short time, and the bus waveformcan be settled rapidly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall drawing of one embodiment of the present invention,showing connection of a system bus and expansion devices.

FIG. 2 shows one embodiment of an input output device supplying power toan expansion device.

FIG. 3 shows one embodiment of a plurality of power supplies forsupplying power to an expansion device.

FIG. 4 shows another embodiment of an input output device supplyingpower to an expansion device.

FIG. 5 shows an example of packaging independent power supply regionsfor expansion devices.

FIG. 6 shows one embodiment of a control device connected to a pluralityof expansion devices.

FIG. 7 shows a connection control timing sequence when logicallyconnecting an expansion device to a system bus.

FIG. 8 shows one embodiment of a device notifying that an expansiondevice has been inserted onto a system bus.

FIG. 9 shows one embodiment of an input/output device using transfergates.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a functional block diagram of an input/output device realizingconnection and disconnection of active lines in an embodiment of thepresent invention.

FIG. 1(a) shows an expansion device 800 connecting to a bus (BUS) and apower supply (POWER). The expansion device 800 includes a MOS switch 300having a plurality of transfer gates, a high impedance maintainingcircuit 350 (Hi-Z HOLD) for controlling high impedance to the MOS switch300 when the expansion device 800 is inserted or removed, and anelectronic circuit 400 (BUS LOAD) connecting to the bus for operation.Further, there is connection means for ensuring that the order ofconnection is the power supply followed by the bus when the expansiondevice 800 is inserted to the bus and power supply, and disconnecting inthe order of the bus followed by the power supply when the expansiondevice is removed. In this case the connection means is shown as longand short pins.

The transfer gates are one type of MOS element. If the gate terminal ofa MOS transfer gate is enabled (close control) a conducting stateresults across the source and drain terminals, while if the gateterminal is disabled, a high impedance state exists across the sourceand drain terminals. The transfer gates can be used as a crossbarswitch, for example, for switching communication lines.

With respect to the power supply, all electronic circuit devices used onthe bus circuit typically share a power supply. However, there is adanger of variations in power supply load at the time of insertion orremoval of expansion devices causing instability in the operation ofother electronic circuits. In order to improve reliability, there is adesire for power supply capacity to be larger than a regular load state,so as to keep fluctuations of the power supply to a steady value in thesystem, even when an expansion device is inserted or removed.

According to the embodiment of the present invention, it is possible toreduce the effects on an operating bus at the time of insertion orremoval of an expansion device 800. Specifically, when an expansiondevice 800 is inserted, initially power is supplied to the expansiondevice 800, and the high impedance maintaining circuit 350 drives thesignal lines of the MOS switch so as to put the MOS switch 300 in a highimpedance state. After that, the MOS switch 300 that has been put in ahigh impedance state is connected to the bus, the bus and electroniccircuits are connected by carrying out external enable control of theMOS switch 300 and the insertion operation is thus completed. When theMOS switch 300 and the bus to which an expansion device is beinginserted are connected, the MOS switch 300 enables insertion of theexpansion device 800 even to an operating bus because the high impedancestate can be guaranteed and a capacitive load can be made small. FIG.1(b) shows a power supply wiring example in order to allow theembodiment to function reliably. Specifically, if a power supply isinitially connected to an electronic circuit 400 having a generallylarge capacitive load, the power supply fluctuates due to current surgecaused by charging of the capacitive load and the operation of the MOSswitch 300 can not be guaranteed. Also, in the event that anotherexpansion device is sharing the power supply, there is a risk that anyeffects will be passed on to the operating bus. At least during theconnection operation, power is supplied from a stable power supplyPOWER_1 to the MOS switch 300 and the high impedance maintaining circuit350, while power is supplied to the electronic circuit 400 from a powersupply POWER_2 that is different from POWER_1. By separating the powersupply systems, the operation of putting the MOS switch 300 into a highimpedance state can be guaranteed at the time of insertion of anexpansion device 800, and also, by separating the power supply POWER_2from a power supply used in normal operation the operation of otherexpansion devices is guaranteed.

Detailed examples of each of the functions will be given in thefollowing. One embodiment of an input/output device realizing connectionand disconnection of active lines according to the present inventionwill now be described below with reference to FIG. 1(b). FIG. 1(c) showsa system bus 100 having a plurality of signal lines, branching wires 200from the system bus 100, a MOS switch 300 (MOS-SW), an electroniccircuit 400 (BUSLOAD) operating by connection to the bus, a controldevice 500 (CNT) for open/close controlling the MOS switch 300, a line600 for open/close control of the MOS switch 300, an expansion device800 separate from a printed substrate for wiring of the system bus 100,a resistor 810 on the expansion device 800 and connected to a negativeopen/close control terminal 242 of the MOS switch 300, connectors 700 a,700 b for connecting the expansion device 800 to the system bus 100, anda main power supply 110 for supplying power to the expansion device 800.A plurality of expansion devices 800 are preferably connected to thesystem bus 100, and in this embodiment an expansion device 800 will bereferred to instead of a plurality of expansion devices 800.

The connectors 700 a, 700 b have a pair of long pins that make contactfirst when an expansion device 800 is inserted and break contact lastwhen it is being removed, and a pair of short pins that make contactlater than the long pins when the expansion device is being inserted andbreak contact before the long pins when the expansion device is beingremoved.

The MOS switch 300 includes a plurality of transfer gates 310 and adriver 320 for driving the gates of the transfer gates 310. The transfergates 310 are connected to the electronic circuit 400 and alsorespectively connected to the branch wires 210˜21 n, through the pairsof short pins (710 a˜71 na, 710 b˜71 nb). The driver 320 is suppliedwith power from a positive power supply section 240 and a negative powersupply section 241 for the input/output device. The positive powersupply section 240 and a negative power supply section 241 for theinput/output device are connected to a stable main power supply 110through the long pin pairs (720 a˜721 a, 720 b˜721 b) One end of theresistor 810 is connected to the open/close control terminal 242 whilethe other end is connected to the positive power supply section 240 forthe input/output device that is provided with power from the main powersupply 110 through the long pin pair (720 a, 720 b). The open/closecontrol terminal 242 is connected to the short pin pair (730 a, 730 b)and also to the controller 500 through the control line 600. Theresistance value of the resistor 810 is preferable made large so as tomake it possible to drive the control line 600 from the controller 500within a sufficiently small time compared to the operating cycle of thesystem bus.

In order for the electronic circuit 400 to transmit a signal to thesystem bus 100, the controller 500 must enable respective transfer gates310 inside the MOS switch 300, by making the control line 600 a “logicalnegative potential” (this will hereinafter be simply referred to as LOW,and similarly a “logical positive potential” will be referred to asHIGH). As a result of this, the electronic circuit 400 is connected tothe system bus 100, and can transmit signal to other electronic devicesconnected to the system bus 100.

The technical concept of the present invention is to guarantee a highimpedance state of input/output lines 220˜22 n at the time an expansiondevice 800 is inserted, without the intervention of the controller 500,by securing the power supply of the MOS switch 300 and the potential ofthe open/close control terminal before the input/output lines 220˜22 nare connected.

In order to do this, means are required for guaranteeing operation ofthe MOS switch 300 and the open/close control terminal before theinput/output lines 220˜22 n are connected, and in this embodiment it isintended to guarantee the connection sequence of the power supply andsignal lines using a connector having long pins, to give stableoperation of the MOS switch 300.

It will now be described how insertion or removal of an expansion device800 without adversely affecting the system bus 100 is realized.

When an operator inserts an expansion device 800 a positive voltage ofthe stable main power supply 110 is initially supplied to the positivepower supply section 240 for the input output device from the pair oflong pins (720 a, 720 b), and at the same time a negative voltage of thestable main power supply is provided to the negative power supplysection 241 from the pair of long pins (721 a, 721 b). At this time,since HIGH is applied to the open/close control terminal 242 of the MOSswitch 300 through the resistor 810, the MOS switch 300 secures thepower supply and is in a disabled state, while the input/output lines220˜22 n are guaranteed in a high impedance state. If an expansiondevice 800 is inserted, the high impedance state input/output lines220˜22 n and the branch wires 210˜21 n are connected through the shortpin pairs (710 a˜71 na, 710 b˜71 nb). After all the pins of theconnector 700 a and connector 700 b have been connected, the controller500 drives the open/close control terminal 242 LOW via the control line600, and the electronic circuit 400 and the system bus 100 areconnected. Because of the above described structure, since theinput/output lines 220˜22 n of the MOS switch 300 are guaranteed to bein a high impedance state when the expansion device 800 is inserted, theinfluence of load variation passed to the system bus is only slight.

Next, in the event that an operator removes an expansion device 800, theoperator first of all supplies an instruction to the controller beforeremoval, the open/close control terminal 242 is driven HIGH through thecontrol line 600, and the electronic circuit 400 and the system bus 100are disconnected. The expansion device 800 is pulled out with the MOSswitch 300 being secured in a disabled state, and first of all the shortpin pairs (710 a˜71 na, 710 b˜71 nb) connected to the branch wires210˜21 n, and the short pin pairs (730 a, 730 b) connected to thecontrol line 600 are disconnected. Even after the plurality of short pinpairs have been disconnected, the input output lines 220˜22 n of the MOSswitch 300 are guaranteed to be in a high impedance state because of thepower supply provided from the long pin pairs (720 a˜721 a, 721 a˜721 b)and the resistor 810 joined to the power supply. Finally, the long pinpairs (720 a˜721 a, 72 ob˜721 b) are disconnected, and removal iscomplete. Similarly to the case when an expansion device 800 isinserted, since the input/output lines 220˜22 n of the MOS switch 300are guaranteed to be in a high impedance state when the expansion device800 is removed, the influence of load variation passed to the system busis only slight.

FIG. 2 is a diagram showing an input/output device realizing connectionand disconnection of active lines, and particularly an input/outputdevice providing power to an expansion device, used in the embodiment ofthe present invention.

As well as the structural elements shown in FIG. 1, FIG. 2 shows areserve charge power supply 120, circuit loads 820˜82 m that represent aload of an expansion device 800 included in an electronic circuit 400,and a circuit power supply section 243 for providing direct power onlyto the circuit loads 820˜82 m from the reserve charge power supply 120through the pair of long pins (722 a, 722 b).

The technical concept of the present invention is to guarantee the powersupply the MOS switch 300, so that input/output lines are reliably putin a high impedance state, preventing, as much as possible, effectscaused by load fluctuations being passed to a main power supply 110 fromwhich expansion devices other than those currently operating arereceiving power, at the time the expansion device 800 is inserted orremoved. In this embodiment, which is intended to achieve the above,there is shown an example in which a positive power supply section 240for an input/output device (MOS switch 300) and a positive power supplysection (in this case the circuit power supply section 243) for devicesother than the input/output device are separated within the expansiondevice 800, and power is supplied to the input/output device positivepower supply section 240 from the main power supply 110, while power tothe circuit power supply section 243 is provided from the reserve chargepower supply 120.

A connection is made from the reserve charge power supply 120 to thecircuit power supply section 243 through the pair of long pins (722 a,722 b) and a diode 830. A connection is also made from the main powersupply 110 to the circuit power supply section 243 through the pair ofshort pins (723 a, 723 b), bypassing the diode 830.

The manner in which adverse effects caused by load variations areprevented from being passed to the main power supply 110 when anexpansion device 800 is inserted or removed will be explained in thefollowing.

When an operator inserts an expansion device 800, power is provided tothe MOS switch 300 from the stable main power supply 110 through thelong pin pairs (720 a˜721 a, 720 b˜721 b). Keeping the input/outputlines of the MOS switch 300 disabled using the stable main power supplyis done in the same way as has already been described above. At the sametime, power is also provided from the reserve charge power supply 120 tothe circuit power supply section 243 through the pair of long pins (722a, 722 b) and the diode 830. In this case, the reserve charge powersupply 120 carries out reserve charging of the circuit loads 820˜82 m.If an expansion device 800 is inserted, power is supplied to the circuitpower supply 243 from the main power supply 110 by the pair of shortpins (723 a, 723 b), and insertion of the expansion device 800 is thuscompleted.

Next, when an operator removes an expansion device 800, first of all theshort pin pair (723 a, 723 b) is disconnected and the main power supplystops supplying power to the load circuits 820˜82 m. At this time,counter-electromotive force caused by the effects of the power supplybeing physically removed is cut out by the diode 830. The plurality oflong pin pairs (720 a˜722 a, 720 b˜722 b) are also separated, andremoval of the expansion device 800 is completed. Here, the design ofthe embodiment is such that it does not matter if the power supplycapacity of the reserve charge power supply 120 is small compared to themain power supply 110. That is, the main power supply 110 is sharedamong a plurality of expansion devices connected to the system bus 100,which means that if the effects on the plurality of expansion devicesare taken into consideration fluctuations caused by variation in load ofthe main power supply 110 must be avoided as much as possible. For thisreason, the supply of power from the stable main power supply 110 shouldbe supplied to an essential minimum of circuits, and at the time ofinsertion or removal, power is supplied only to the MOS switch 300 whichdemands reliable operation. On the other hand, various electroniccircuits are included within the expansion device, and it can generallybe said that the initial charging charge immediately before an expansiondevice is inserted is zero. If the main power supply 110 is directlyconnected to these electronic circuits, a surge current flows initiallycharging the electronic circuits, and there is a danger of fluctuationsin the main power supply 110.

The reserve charge power supply 120 is arranged to prevent the abovedescribed fluctuations, and the reserve charge is carried out by thereserve charge power supply 120, and the structure is such that the mainpower supply 110 is connected after the surge current has beenstabilized. In this embodiment, the structure is such that power issupplied from the reserve charge power supply 120 to the long pins, andfrom the main power supply to the short pins. For the above describedreason, a designer will preferably design the capacity of the reservecharge power supply 120 taking into consideration the size of the surgecurrent of the expansion device 800 so that fluctuations are made to beat a level that can be approved for the system configuration.

Another embodiment of an input/output device for connection anddisconnection of active lines according to the present invention, andparticularly which provides power to an expansion device, is shown inFIG. 3 and will be described below.

FIG. 3(a) differs from the structure of FIG. 2 in that the reservecharge power supply 120 is replaced with a capacitor 120′, and a surgecurrent limiting circuit 121 has been added.

FIG. 3(b) shows the structure of the a surge current limiting circuit121, and shows a diode 122 and a resistor 123 connected between a mainpower supply line 230 connected to the main power supply 110, and areserve charge power supply line 232 connected to the capacitor 120′.

The feature of this embodiment is the reserve charge power supply 120has been replaced by the capacitor 120′ that is charged from the mainpower supply 110.

The behaviour of the two power supplies will now be described below.First of all, the capacitor 120′ is charged from the main power supply110 and is charged to approximately the same potential as the main powersupply 110. When an expansion device 800 has been inserted, the initialcharging current for the circuit loads inside the expansion device 800is provided from the capacitor 120′. From FIG. 2 and FIG. 3, it can beseen that the instant the long pin pair (722 a, 722 b) are connectedthere is a transfer of electrical charge transfer across the capacitor120′ and the circuit loads 820˜82 m. After that, charging is carried outfrom the main power supply 110 at a time constant according to theresistor 123 and the combined capacitance of the capacitor 120′ and thecircuit loads 820˜82 m, until the long pin pair (723 a, 723 b) areconnected. Accordingly, taking the previously mentioned time coefficientinto consideration, fluctuations in the main power supply 110 caused bysurge current can be prevented by giving the capacitor 120′ asufficiently large value.

Another embodiment of an input/output device for connection anddisconnection of active lines according to the present invention, andparticularly which provides power to an expansion device, is shown inFIG. 4 and will be described below.

Compared to the constructional elements shown in FIG. 2, the reservecharge power charge 120 has been removed in FIG. 3, and the resistor 831is arranged in series with the diode 830. Also, there is a directconnection from the main power supply 110 to the pair of long pins (722a, 722 b).

The feature of this embodiment is that the positive power supply section240 for the input/output device (in this case the MOS switch 300) andthe positive power supply section (in this case the circuit power supplysection 243) for circuits other than the input/output device areseparated inside the expansion device, and power is provided to thepositive power supply section 240 and the circuit power supply section243 from the main power supply 110.

A connection is made between the main power supply 110 and the circuitpower supply section 243 via the pair of long pins (722 a, 722 b), thediode 830 and the resistor 831, and a connection is made between themain power supply 110 and the circuit power supply section 243 via thepair of short pins (723 a, 723 b), bypassing the diode 830 and theresistor 831.

The prevention of adverse effects caused by load variations being passedto the main power supply 110 when an expansion device 800 is inserted orremoved will be described in the following.

When an operator inserts an expansion device 800, power is provided fromthe stable main power supply to the MOS switch 300 through the pair oflong pins (720 a˜721 a, 720 b˜721 b). Maintaining the disabled state ofthe input/output lines of the MOS switch 300 by the stable main powersupply is the same as has been described in the previous embodiments. Atthe same time, power is provided from the main power supply 110 to thecircuit power supply section 243 through the pair of long pins 722 a,722 b, the diode 830 and the resistor 831. Here, the main power supply110 carries out reserve charging of the circuit loads 820˜82 m at a timecoefficient determined by the resistor 831 and the combined capacitanceof the circuit loads 820˜82 m. Further, when the expansion device hasbeen inserted, power is provided from the main power supply 110 to thecircuit power supply section 243 by the short pin pair (723 a, 723 b),and insertion of the expansion device 800 is completed.

When an operator removes an expansion device 800, first of all the shortpin pair (723 a, 723 b) are separated, and the main power supply 110stops providing power to the circuit loads 820˜82 m. At this time, acounter-electromotive force caused by the effects of disconnection ofthe power supply is cut out by the diode 830. A plurality of long pinpairs (720 a˜722 a, 720 b˜722 b) are also separated, and removal of theexpansion device 800 is completed.

In the case of the embodiment in FIG. 4, compared to FIG. 2, there is noreverse charge power supply, and the resistor 831 is added as required.Because of this, a resistor 831 is preferably provided to limit surgecurrent when the expansion device 800 is inserted, and the value of theresistor 831 is preferably made sufficiently large. However, it must beconsidered that before connection of the short pin pair (723 a, 723 b),it is necessary to sufficiently charge the circuit loads 820˜82 m, and agood balance must be set between an upper limit of the surge current andthe size of a time coefficient.

An example of implementation of an input/output device for connectionand disconnection of active lines according to the present invention,and particularly which provides power to an expansion device, is shownin FIG. 5.

FIG. 5 can be applied to FIG. 2 or FIG. 4, and in this case theembodiment of FIG. 4 will be described.

The feature of this embodiment is that the positive power supply section240 for the input/output device (in this case the MOS switch 300) andthe positive power supply section for parts other than the input/outputdevice (the circuit power supply section 243) are separated within theexpansion device, and respective different positive power supply regionsare provided on a printed substrate 900.

FIG. 5 shows that the long pin 720 b and the short pin 723 b areconnected to respective positive power supply regions 850, 851 on theprinted substrate 900 (these regions are shown as hatched regions in thedrawing), and that a connection is made from the long pin 722 b to thepositive power supply region 851 through the diode 830 and resistor 831.

Because both power supply regions are provided separately, with a space(slit) that is not part of either power supply region being interposedbetween the positive power supply region for the input/output device 850and the circuit load positive power supply region 851, the power supplyregions are prevented from affecting the main power supply 110, and theeffects of stopping fluctuations in the power supply are improved. Also,by using a multilayer printed substrate respective power supply regionscan be provided on separate layers instead of on the same surface.

In this embodiment, because the input/output device power supply section240 and the circuit power supply section 243 mutually interfere with themain power supply 110, the long pin pair (720 a, 720 b) and the long pinpair (722 a, 722 b) or the short pin pair (723 a, 723 b) are preferablyarranged on the connectors (700 a, 700 b) so as to be physicallyseparated as much as possible. If possible, the long pin pair (720 a,720 b) and the long pin pair (722 a, 722 b) are disposed on the two endsof the connector.

An embodiment an input/output device of the present invention, andparticularly a control device for carrying out open/close control of theMOS switch, is shown in FIG. 6.

FIG. 6 shows a control device 500 and sections of the expansion devicesrelated to open/close control. In this drawing there are shown thecontrol device 500 (CNT) for carrying out open/close control of the MOSswitches 300, a service processor 510 (SVP) for supplying operatorinstructions to support operation of the control device 500, aconnection monitoring section 520 (SLOT ACK) for monitoring a connectionstate of an expansion device 800, an open/close section 530 (GATE CNT)for carrying out the open/close operation of the MOS switches 300, aconnection determination section 540 (CONDITION) for determiningconnection of the MOS switches 300, an operating instruction logicsection 550, a reference signal generator 561 (PLL) for generatingreference signal 560 by extracting a signal on the system bus 100, acontrol line 600 for transmitting open close control, a slot conditionline 610 for transmitting a connection status of the expansion device800, and a slot status output section 840 (Slot IN) for outputting aconnection status of the expansion device 800.

The connection monitoring section 520 has a connection status register521. The open/close section 530 has an open/close control register 531.

Operation of the control device 500 when an expansion device 800 isinserted will now be described below.

When an operator inserts an expansion device 800, if the expansiondevice is initially inserted on to the system bus 100, the fact that ithas been inserted is notified from the slot status output section 840 tothe control device 500 using the slot status line 610. If insertion ofthe expansion device 800 is sensed, the connection monitoring section520 sets the status of the expansion device 800 in the connection statusregister 521 and passes an interrupt to the connection determinationsection 540. If a predetermined condition is satisfied, the connectiondetermination section 540 that has received the interrupt issues aconnection instruction to the operating instruction logic section 550.In this case, an instruction from the service processor 510, aninterrupt generated after a fixed time has elapsed, or notification ofcompletion of reset processing for the expansion device 800 concerned,etc. is the fixed condition, and the operating instruction logic section550 preferably has means for confirming these, as required. Theoperating instruction logic section 550 writes “close” information forclosing the MOS switch 300 to a region of the open/close registercorresponding to the expansion device 800 that has been inserted, usingsignals from the connection determination section 540 and the connectionmonitoring section 520. The open/close section 530 selects a controlline 600 of an expansion device 800 corresponding to the region that hasbeen written to and drives the open/close control terminal 242 of theMOS switch 300 LOW. An inserted expansion device 800 is connected to thesystem bus 110 by the above described operation. A main processor forcarrying out system management completes configuration control of thesystem bus 110, performs setting of the internal registers inside therelevant expansion device 800 etc, and after that the system switches tonormal operation.

When an operator removes an expansion device 800, the MOS switch 300 ofthe expansion device 800 concerned must first of all be disconnected inorder to minimize effects on the system bus 110 caused by the removal.To do this, the connection determination section 540 must first beinformed of the expansion device 800 to be removed, and this can be doneusing a disconnection request interrupt from the main processor managingthe system, an instruction input by the operator from the serviceprocessor 510, an error report interrupt from the expansion device 800concerned, etc. The connection determination section 540 that hasconfirmed the expansion device 800 to be removed issues a command thatthe relevant expansion device 800 is to be disconnected to the operatinginstruction logic section 550. The operating instruction logic section550 writes “open” information to a region of the open/close controlregister 531 corresponding to the expansion device being removed, usingsignals from the connection determination section 540. The open/closesection 530 selects a control line 600 of the expansion device 800corresponding to the region that has been written to, and drives theopen/close control terminal 242 of the MOS switch 300 HIGH. An insertedexpansion device 800 is disconnected from the system bus 110 using theabove described procedure. Further, an expansion device that can beremoved is physically disconnected from the system by an operator. Amain processor for carrying out system management completesreconfiguration control of the system bus 110, performs setting of theinternal registers inside the relevant expansion device 800 etc, andafter that the system switches to normal operation.

An embodiment of a method of connecting an input/output device of thepresent invention, and particularly an expansion device, to a systembus, is shown in FIG. 7, and will be described below.

In this embodiment, when the expansion device is physically connected ordisconnected to or from the system bus, the timing of the connection ordisconnection is set so that signal transmissions currently in progresson the system bus are not affected, and disturbance of the waveform issettled within a period which does not affect the extraction of signalfrom the bus.

FIG. 7 shows the timing of connecting an expansion device 800 to thesystem bus 100, and shows examples of operating waveforms of a referencesignal 560, the control line 600 and the system bus 100. In thisembodiment, a signal on the system bus 100 is defined and taken in onthe rising edge of the reference signal 560. The period of the referencesignal 560 of the system bus 560 is Tclk1020, and the required signalset up time on the system bus 100 is Tsu1010.

The reference signal 560 is connected to the open/close section 530 thatdrives the control line 600. To logically connect the open/close section530 the electronic circuit 400 inside the expansion device 800 and tothe system bus 100, the control line 600 is driven LOW. In this case theopen/close section 530 sets the control signal 600 LOW in synchronismwith the rising edge of the reference signal 560 (1030). As a result,the MOS switch 300 is put in a conducting state, and since theelectronic circuit 400 is connected to the system bus 100 signaldisturbance occurs on the system bus (1040). However, even if signaldisturbance occurs, if the signal wave form is settled before the risingedge of the next reference signal 560, i.e. within Tsu there will be noeffect on the signal taken in at the rising edge of the reference signal560. As a result, the control device 500 can connected the expansiondevice 800 without inhibiting signal transmission on the bus.

An embodiment of an input/output device realizing connection anddisconnection of active lines of the present invention, and particularlya slot status output section for notifying that an expansion device hasbeen inserted, is shown in FIG. 8, and will be described in thefollowing.

FIG. 8 shows one structural example of a slot status output section 840.The slot status output section 840 is provided between the expansiondevice 800 and the control device 500, and a slot status line 610 isconnected to a negative power supply line 241 within the expansiondevice 800, via a pair of short pins (731 a, 731 b). The slot statusline 610 is also connected to a positive power supply section, forexample the main power supply section 230, via a resistor 611 inside theexpansion device 800.

The operation of the slot status output section 840 when an expansiondevice 800 is inserted will now be described below.

Before an operator insert an expansion device 800, the slot status line610 outputs HIGH because it is pulled up by resistor 611 connected tothe positive power supply. This enables the control device 500 toconfirm that there is no expansion device 800 connected on the systembus 100. When the operator inserts the expansion device 800, theplurality of long pin pairs are connected, and after the power supplypotential has been defined the short pin pairs are connected. If theshort pin pair (731 a, 731 b) is connected the slot status line 610 isconnected to the negative power supply section 241 and LOW is output. Asa result, the control device 500 confirms that the expansion device 800has been inserted onto the system bus 100.

When an expansion device 800 is removed, the situation is the reverse tothat described above, and before removal the slot status line 610 isoutputting LOW. Removal of the expansion device 800 causes HIGH to beoutput, and as a result of this the control device 500 confirms that theexpansion device 800 has been removed.

FIG. 9 shows one embodiment of an input/output device of the presentinvention, which will be described in the following.

FIG. 9 shows a system bus 100 having a plurality of signal lines, a tap200 which is a branch off the system bus 100, a MOS switch 300 (MOS-SW),and an electronic circuit 400 (BUSLOAD) capable of operating by directconnection to the bus.

The technical concept of the present invention is to reducing thesettling time of signal waveforms on a bus when a conventionalelectronic circuit is directly connected to a bus and reducing waveformfluctuation by inserting a MOS switch between the bus and the electroniccircuit and disposing the MOS switch 300 as close to the bus aspossible, and making electronic circuits in which signal wiring from aconventional bus is restricted in length more capable of beingdisconnected than in the related art.

Since the MOS switch 300 is always enabled, the input of an open/closecontrol driver 320 is connected to the negative power supply 241 via aresistor.

With regard to the respective lengths LA1˜LAn of each signal line 210˜21n including the tap 200, the lengths are made as short as possible forthe implementation. When the MOS switch 300 has been enabled, signals tobe transmitted on the system bus are generally subject to the effects ofreflection from 3 places, i.e. (1) from the pins of the MOS switch 300on the side of the system bus 100, (2) from the pins of the MOS switch300 on the side of the electronic circuit 400, and (3) from the outputpins of the electronic circuit 400. In this embodiment, since the worsteffects on the bus signal transmission waveforms are caused by thelengths LA1˜LAn of (1), reduction in (1) contributes greatly to settlingthe bus signal waveforms. The upper limit of the lengths LA1˜LAn isdetermined to be in a range in which signal logic can be correctlytransmitted by associated electronic circuits 400, taking intoconsideration the effects of operating frequency and reflection etc. ofthe system bus 100 and the total extension of the system bus 100, etc.

For example, a bus system employing 5v, or more specifically in a bussystem with specifications of a bus propagation time of less than 11 ns,bus characteristic impedance of 60˜100 (, electronic circuit input pincapacitance of less than 16 pF, and a maximum number of connectedcircuits being 10, the lengths LA1˜LAn are from) to 1.5 inches, but whenthe electronic circuits are packaged, wiring in the normal way isdifficult.

Even when the maximum number of electronic circuits 400 are connected,the MOS switches 300 are disposed between respective electronic circuitsand the system bus 100 with the lengths LA1˜LAn being between 0 and 1.5inches so as to secure the HIGH level and LOW level of the signalwaveform within the bus propagation time. In this case, the electroniccircuits do not need to be on the same backplane as system bus 100. Bymaking the input pin capacitance of the MOS switch 300 small compared tothe electronic circuits, it is possible for the method of the presentinvention to have a larger number of connections than can be achieved bysimply connecting electronic circuits 400 to the system bus, even in thecase where the electronic circuits are for expansion devices on adifferent backplane.

On the other hand, by arranging the MOS switches 300 close to the systembus and satisfying the bus specifications, the electronic circuits 400can be wired with lengths LB1˜LBn of more than 1.5 inches, butpreferably less than 10 inches.

As has been described above, by distributing the MOS switch 300 betweenthe electronic circuits 400 and the system bus 100 within a range takingthe effects of reflection into consideration, signals output from theelectronic circuits are output onto the system bus 100 by way oftransfer gates 310 of the MOS switches 300, and at this time signals onthe system bus are mainly effected by reflections from both ends of thesystem bus 100 and from the input terminals of other MOS switches 300.Multiple reflections of bus signals is suppressed by making the lengthsLA1˜LAn short, and accordingly the bus signal waveforms are convergedand settled rapidly, and high speed bus applications are possible.

INDUSTRIAL APPLICABILITY

According to the present invention, an input output device capable ofconnecting and disconnecting active lines can be realized in whichinsertion or removal of an expansion device does not upset transmissionof bus signals for other electronic circuits on a bus capable of highspeed operation, because disabling is ensured at the time of insertionor removal using transfer gates of small signal delay in theinput/output circuit.

Further, according to the present invention, it is possible to realizean input/output device capable of connecting and disconnecting activelines in which there are multiple power supplies, the effects on a powersupply at the time of insertion or removal are reduced, and theoperation of electronic circuits that are not involved in the insertionor removal does not become unstable.

Still further, the input/output device of the present invention can beapplied to a high speed bus because the bus operation waveform israpidly settled by arranging inputs of transfer gates at positions thatare a fixed short distance from a bus constituted by the input/outputsections of electronic circuits.

We claim:
 1. A control device capable of connecting and disconnectingwith an expansion device, comprising: a connection monitoring section toestablish connection status of the expansion device to a connectionstatus register when the expansion device is connected, and to output aninterrupt signal based on the established connection status; aconnection determination section to output a connection signal based onthe interrupt signal and a predetermined condition; an operatinginstruction section to form close information to close an open/closecontrol element to control signal transmission of electric circuits inthe expansion device based on the connection signal and interruptsignal, and to output the close information; and an open/close sectioncomprising an open/close control register to store control informationof the open/close control element, wherein the operating instructionsection establishes the close information to the open/close controlregister of the open/close section, and wherein the open/close sectionoutputs the established close information to the connected expansiondevice.
 2. A control device according to claim 1, wherein the connectiondetermination section outputs a disconnection signal that the expansiondevice is to be disconnected, wherein the operating instruction sectionforms open information to open the open/close control element, andestablishes the open information to the open/close control register, andwherein the open/close section outputs the established open informationto the expansion device.
 3. A control device capable of connecting anddisconnecting with an expansion device, comprising: a connectionmonitoring means for establishing a connection status of the expansiondevice to a connection status register when the expansion device isconnected, and for outputting an interrupt signal based on theestablished connection status; a connection determination means foroutputting a connection signal based on the interrupt signal and apredetermined condition; an operating instruction means for formingclose information for closing an open/close control means forcontrolling signal transmission of electric circuits in the expansiondevice based on the connection signal and interrupt signal, and foroutputting the close information; and an open/close means comprising anopen/close control register means for storing control information of theopen/close control means, wherein the operating instruction meansestablishes the close information to the open/close control means of theopen/close means, and wherein the open/close means outputs theestablished close information to the connected expansion device.
 4. Acontrol device according to claim 3, wherein the connectiondetermination means outputs a disconnection signal that the expansiondevice is to be disconnected, wherein the operating instruction meansforms open information for opening the open/close control means, andestablishes the open information to the open/close control registermeans, and wherein the open/close means outputs the established openinformation to the expansion device.